<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>天气案例_监视属性_简写</title>
    <script type="text/javascript" src="../js/vue.js"></script>
</head>
<body>
    <div id="root">
        <h2>今天天气很{{info}}</h2>
        <button @click="changeMeather">切换天气</button>
    </div>
</body>
<script type="text/javascript">
    Vue.config.productionTip=false;
    const vm=new Vue({
        el:'#root',
        data:{
            isHot:true,
        },computed: {
            info(){
               return this.isHot?'炎热':'凉爽'
            }
        },
        methods: {
            changeMeather(){
                this.isHot=!this.isHot
            }
        },
        watch:{
            /*isHot:{
                //正常写法
                //immediate:true, //初始化时让handler调用一下
                //handler调用：当isHot发生改变时
                //deep:true,  //深度监视
                handler(newValue,oldValue){
                    console.log('isHot被修改了',newValue,oldValue)
                }
            },*/
            
            //简写
            /*isHot(newValue,oldValue){
                console.log('isHot被修改了',newValue,oldValue)
            }*/
        }
    })
            //正常写法
            /*vm.$watch('isHot',{
                immediate:true, //初始化时让handler调用一下
                deep:true,  //深度监视
                handler(newValue,oldValue){
                    console.log('isHot被修改了',newValue,oldValue)
                }
            })*/

            vm.$watch('isHot',function(newValue,oldValue){
                console.log('isHot被修改了',newValue,oldValue)
            })
</script>
</html>